Saturday 23 June 2012 19.05 EDT
First published on Saturday 23 June 2012 19.05 EDT

I have sometimes wondered why Alastair Campbell has still to take up a proper job since leaving Downing Street almost a decade ago. On reading the latest instalment of his engrossing diaries, I think I'm beginning to understand why.

The spin maestro's fourth tranche of musings covers the period from 9/11 – beginning on that fateful date – and ending at the moment of his departure from Tony Blair's right-hand side. The miserablist figure of Gordon Brown looms large; public sector reform is deadlocked. But the issue that dominates is, inevitably, Iraq.

As a first draft of history, albeit a highly partial one, this account is hard to beat. Campbell packs in all the events and the colourful cast of characters, enhanced by often caustic one-liners. Brown is the perennial brooder. In June 2002, a full five years before Blair finally upped sticks, Campbell reported: "All GB ever asked him these days was when he was going." Few are spared Campbell's disdain. Christopher Meyer, Britain's ambassador to Washington, is seen as prone to tantrums. Clare Short is a pain in the prime ministerial rear side. Piers Morgan, then editor of the Mirror, was wooed almost as assiduously as were the Murdochs, but according to Campbell, it was difficult for Blair to have a conversation with him "as the only thing he was really interested in was himself".

The list of targets goes on: Adam Boulton, with whom Campbell subsequently came to blows, is "as sour as ever"; Andrew Marr was nothing more than a "a PR man for the Beeb". Nick Robinson, then at ITN, was "a jerk".

Campbell's loathing of much of the media is visceral. The Sunday papers are dismissed as "millions of words of fuck all", while the latest so-called scandal to engulf Blair was nothing more than the "next crapola to deal with". By the end of his time in No 10, he had become obsessed with the coverage of Iraq. His bete noire was Andrew Gilligan, whose claim that Campbell had sexed up the infamous dossier set off a chain of events that led to the death of Dr David Kelly, the Hutton inquiry, the dismemberment of the BBC and Campbell's resignation.

I was hoping that Campbell might shed some new light on his thinking behind Iraq and other major decisions. There was some, but not much. In a brief episode that featured prominently in the serialisation of the book, Campbell reveals how hard Rupert Murdoch pushed Blair in a series of phone calls not to go soft on the war. But there was no prospect of that happening anyway. On the compromises that may, or may not, be an unavoidable part of government, he sheds little light about his own views. There is no shortage of blokey-jesty comments about Blair's bizarre choice of clothes, but precious little new about the man himself. Too often the narrative is confined to: A meets B, slags off C. Perhaps the format of a diary militates against longer analysis, but I suspect he limited his more critical observations out of loyalty.

Campbell writes with disarming frankness about his many dark days and nights; he even mentions rows with his wife Fiona Millar. But he explains them within the narrower context of her pleading with him to quit, rather than the substance of the Iraq war that tore many friends and families apart. Perhaps in later writings he will go beyond the fatuous Blairite mantra "we did what we thought was right".

Yet for all my criticisms, I was beguiled by the book and the author's brutally honest account of himself. Three things helped him get out of bed in the morning: running, his family and his unswerving dedication to the Blair cause. He charts his preparations for the marathon with a compulsiveness that was part of his coping strategy for his alcoholic past and depressive present.

Indeed, I would buy this book for one passage alone. It was in Crawford, Texas, in April 2002, during the gathering at the presidential ranch at which Blair gave the Americans the green light for the eventual military campaign (little of which the author mentions). Campbell was chatting to George W Bush, during a break in the official meetings. "I asked him how much he drank. He said two or three beers a day, a bit of wine, some bourbon… I went through the kind of quantities I was drinking at the end and said they dwarfed his efforts. I said that having a breakdown and not drinking had been the best thing that ever happened to me. It was like seeing the light? But you still don't believe in God? he asked. No I don't."

In August 2003, at the height of the Hutton drama, and with the spotlight firmly on him, Campbell finally had enough. He describes his resignation with the same abbreviated style that permeates the book. A few weeks earlier he had received a note from Rebekah Brooks, urging him to "hang in… you've done nothing wrong, told the truth, more principles than these other people". The bond between the Blair and the Murdoch clans was unshakable.

Amid all the good luck wishes he received, including from Robin Cook – whose resignation over Iraq is one of the great moments of principle of modern British political life – the best he got from Brown was a phone message from his secretary thanking him for his services.

I had little time for the more slippery operators in Blair's entourage, even less for Brown's thugs. Campbell's evident personality flaws, coupled with his political passions, made him a far more intriguing character than most around him. They have equally ensured that his diaries will be required reading for the New Labour era.

Alastair Campbell, the once ferocious spin doctor, is starting to feel like a 'proper' novelist. He has just published his third, and is reluctant to talk politics. But there's no getting away from Syria